1. Field of the Invention
The present invention relates to an apparatus for and a method of extracting an image of one object by comparing obtained images of the object, the images by a plurality of imaging units.
2. Description of the Related Art
There has been developed a vehicle vicinity monitoring apparatus for obtaining images of one object with two imaging units mounted on a vehicle, for example, either measuring the distance up to the object based on the parallax between the obtained images, or measuring the position in an actual space of the object with respect to the vehicle, and informing the driver of whether there is an obstacle ahead of the vehicle or not (see Japanese Laid-Open Patent Publication No. 2003-216937).
For extracting the same object from the two images obtained by the two imaging units, correlative calculations are used to determine the sum of absolute differences (SAD) between image data of an object area identified in one of the images and image data of the other image, and to regard an area where the sum is minimum as an object area in the other image.
The imaging units, each comprising a CCD camera or the like, may not necessarily have identical video characteristics because they tend to have different optical characteristics and different photoelectric conversion characteristics of respective pixels and photoelectrically converted video signals tend to contain noise. If the above correlative calculations are performed on image signals from the two imaging units whose video characteristics are different from each other, then the background of the object in question may possibly be recognized in error, and different objects may possibly be judged as the same object.